.TH std::length_error 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::length_error \- std::length_error

.SH Synopsis
   Defined in header <stdexcept>
   class length_error;

   Defines a type of object to be thrown as exception. It reports errors that result
   from attempts to exceed implementation defined length limits for some object.

   This exception is thrown by member functions of std::basic_string and
   std::vector::reserve.

   std-length error-inheritance.svg

                                   Inheritance diagram

.SH Member functions

   constructor   constructs a new length_error object with the given message
                 \fI(public member function)\fP
   operator=     replaces the length_error object
                 \fI(public member function)\fP

std::length_error::length_error

   length_error( const std::string& what_arg ); \fB(1)\fP
   length_error( const char* what_arg );        \fB(2)\fP
   length_error( const length_error& other );   \fB(3)\fP (noexcept since C++11)

   1) Constructs the exception object with what_arg as explanatory string. After
   construction, std::strcmp(what(), what_arg.c_str()) == 0.
   2) Constructs the exception object with what_arg as explanatory string. After
   construction, std::strcmp(what(), what_arg) == 0.
   3) Copy constructor. If *this and other both have dynamic type std::length_error
   then std::strcmp(what(), other.what()) == 0. No exception can be thrown from the
   copy constructor.

.SH Parameters

   what_arg - explanatory string
   other    - another exception object to copy

.SH Exceptions

   1,2) May throw std::bad_alloc.

.SH Notes

   Because copying std::length_error is not permitted to throw exceptions, this message
   is typically stored internally as a separately-allocated reference-counted string.
   This is also why there is no constructor taking std::string&&: it would have to copy
   the content anyway.

   Before the resolution of LWG issue 254, the non-copy constructor can only accept
   std::string. It makes dynamic allocation mandatory in order to construct a
   std::string object.

   After the resolution of LWG issue 471, a derived standard exception class must have
   a publicly accessible copy constructor. It can be implicitly defined as long as the
   explanatory strings obtained by what() are the same for the original object and the
   copied object.

std::length_error::operator=

   length_error& operator=( const length_error& other );  (noexcept since C++11)

   Assigns the contents with those of other. If *this and other both have dynamic type
   std::length_error then std::strcmp(what(), other.what()) == 0 after assignment. No
   exception can be thrown from the copy assignment operator.

.SH Parameters

   other - another exception object to assign with

.SH Return value

   *this

.SH Notes

   After the resolution of LWG issue 471, a derived standard exception class must have
   a publicly accessible copy assignment operator. It can be implicitly defined as long
   as the explanatory strings obtained by what() are the same for the original object
   and the copied object.

Inherited from std::logic_error

Inherited from std::exception

.SH Member functions

   destructor   destroys the exception object
   \fB[virtual]\fP    \fI(virtual public member function of std::exception)\fP
   what         returns an explanatory string
   \fB[virtual]\fP    \fI(virtual public member function of std::exception)\fP

   Defect reports

   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.

     DR    Applied to         Behavior as published               Correct behavior
   LWG 254 C++98      the constructor accepting const char*  added
                      was missing
                      the explanatory strings of             they are the same as that
   LWG 471 C++98      std::length_error's                    of the
                      copies were implementation-defined     original std::length_error
                                                             object

.SH See also

   resize changes the number of characters stored
          \fI(public member function of std::basic_string<CharT,Traits,Allocator>)\fP
